The present application is based on and claims priority from Japanese Patent Application 2003-42649, filed Feb. 20, 2003, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid level detecting device and, particularly a fuel level detecting device for a vehicle.
2. Description of the Related Art
JP-A-2002-168675 discloses a liquid level detecting device which includes a float arm having a float, a resinous arm holder which holds the float arm, a metal plate member which is fixed to the arm holder to move together and has a contact to slide on a sliding surface of a circuit board. The contact is biased against the sliding surface of the circuit board by the elasticity of the metal plate. Thus, the liquid level can be detected by the position of the contact. In the disclosed liquid level detecting device, the arm holder has a pin and the metal plate has a hole so that the metal plate can be fixed to the arm holder when the pin is force-fitted to the hole. The hole is burred at the inner surface thereof to increase the contact surface with the pin.
However, if the hole is burred, the diameter of the hole has to be increased excessively in order to prevent the metal plate from cracking or deforming. This increases the size of the liquid level detecting device. Otherwise, it is difficult to provide a contact that indicates an accurate position.
Therefore, a main object of the invention is to provide a compact liquid level detecting device that indicates an accurate liquid level.
Another object of the invention is to eliminate burring from the engagement hole, thereby reducing the size of the liquid level detecting device.
According to a main feature of the invention, a liquid level detecting device to be disposed in a liquid tank includes a body, a float arm having a float to be disposed in liquid, a resinous arm holder fixed to the body to hold the float arm so that the float arm moves as a level of the liquid changes, a circuit board fixed to the body, an elastic metal plate member having a sliding contact which slides on a sliding surface of the circuit board under a biasing force and a fixing member for fixing the elastic metal plate member to the arm holder, whereby the level of the liquid is indicated by the position of the sliding contact on the sliding surface. In the above constructed liquid level detecting device, the resinous arm holder has an engagement hole portion and the fixing member includes at least a pair of claws which extends along a slit formed between them and is inserted into the engagement hole portion so that the pair of claws elastically deforms in a direction to narrow the slit.
Therefore, the elastic metal plate member can be fixed to the arm holder under a biasing force acting in two different directions, so that burring is not necessary to fix the metal plate to the arm holder.
The fixing member of the above constructed liquid level detecting device may have two pairs of claws which respectively extend in opposite directions. In that case, the engagement hole portion has a pair of holes into which the two pairs of claws are inserted. Preferably, each of the engagement holes is rectangular. Therefore, the metal plate member can be prevented from rotating about an axis that is perpendicular to the surface thereof.
The resinous arm holder and the elastic plate member of the above constructed liquid level detecting device may respectively have a fixing pin and a through hole. In that case, the elastic plate member is fixed to the arm holder by the fixing pin. Therefore, the liquid level detecting device can be made compact.
In the above constructed liquid level detecting device, the fixing member may further include a projecting portion which projects from a base portion toward the engagement hole in the width direction thereof. Therefore, projecting portion functions as a power point and the base portion functions as a fulcrum.